The present invention relates to a yarn winder comprising rotatable bobbin holders supported on a body frame, the bobbin holders each having bobbins installed thereon and around which packages are formed, and in particular, to a yarn winder that can suppress its own vibration.
A representative example of a yarn winder of this kind is a take-up winder. The take-up winder comprises rotatable bobbin holders supported in such a manner as to project from a body frame, the bobbin holders each having bobbins installed thereon and around which packages are formed, and a bracket supported in such a manner as to project from the body frame and holding a roller that rotates in contact with the package, wherein the interval between the bobbin holder and the roller can be varied. By rotationally driving either the roller or the bobbin holder, the package is formed on the bobbin in such a manner as to grow gradually thicker. Since a yarn is wound at a constant winding speed, the rotation speed of the roller in contact with the package is constant. As the package grows thicker and thicker, the rotation speed of the bobbin holder decreases. At the same time, the interval between the bobbin holder and the roller widens.
In such a take-up winder, the bobbin holder, which rotatably holds the massive package, vibrates and the vibration is transmitted to the roller which is in contact with the package and the body frame, thereby vibrating the entire take-up winder. The rotational frequency of the bobbin holder decreases with an increase in the size of the package. Alternatively, the rotational frequency increases consistently with a winding speed of the take-up winder. Take-up winders are required to accommodate larger packages and to wind a yarn at a higher speed, so that recent take-up winders cover a wide range of rotational frequencies. Under these circumstances, a winding operation is performed in such a manner as to slowly traverse the natural frequency of the take-up winder, thereby causing the winder to vibrate.
Vibration suppressing devices are used to suppress this vibration. A vibration suppressing device has been proposed which uses a dynamic vibration reducer attached to a neighborhood of a tip of the above described bracket. The dynamic vibration reducer is constructed by combining a viscoelastic material and a mass. By setting the resonance frequency of the dynamic vibration reducer equal to a neighborhood of the resonance frequency of the take-up winder, the resonance of the take-up winder is suppressed.
Due to differences among individual take-up winders and temporal changes, however, the resonance frequency of the take-up winder is inconstant. On the other hand, the resonance frequency of the dynamic vibration reducer is determined by the viscoelastic material and the mass. It is thus difficult to equalize the resonance frequency of the take-up winder with that of the dynamic vibration reducer. When the characteristics of the take-up winder do not match those of the dynamic vibration reducer, heavy vibration may occur. In addition, since the dynamic vibration reducer has a viscoelastic material such as rubber, temporal changes in rubber change the frequency characteristic of the dynamic vibration reducer in such a manner that its frequency deviates gradually from the resonance frequency of the take-up winder, resulting in an increase in the vibration of the take-up winder. Thus, it is difficult to set and manage the characteristics of the take-up winder and the dynamic vibration reducer so that the dynamic vibration reducer is effective on the take-up winder. Even if a vibration suppressing function can be provided during a short period, maintaining this function during a long-term operation is in fact difficult.
The present invention is provided in view of these problems, and it is an object thereof to provide a yarn winder having a vibration suppressing device that can provide a vibration suppressing function for the yarn winder over a long period despite minor differences in vibration characteristic among individual yarn winders.
The present invention that attains the above object is a yarn winder comprising rotatable bobbin holders supported on a body frame, the bobbin holders each having bobbins installed thereon and around which packages are formed, the yarn winder being characterized in that an impact damper comprising a mass body and a regulation member for holding the mass body in such a manner as to have degrees of freedom is provided in a site that vibrates as the bobbin holder is rotated.
The mass body and regulation member of the impact damper collide against each other to convert vibration energy into thermal energy for absorption, so that even if a vibration characteristic of the impact damper does not match that of the yarn winder, the impact damper can absorb vibration as long as the vibration is heavy. Thus, when the impact damper is provided in a site of the yarn winder where heavy vibration occurs and where the damper is easily mounted, vibration is continuously suppressed as long as it is heavy. It is important that the mass body operates separately from the vibration of the yarn winder.
The present invention is a yarn winder wherein the degrees of freedom of the mass body are provided in a plane perpendicular to a rotational axis of the bobbin holder.
In the yarn winder comprising the rotatable bobbin holders supported on the body frame, the bobbin holders each having the bobbins installed thereon and around which the packages are formed, heavy vibration occurs in the plane perpendicular to the rotational axis of the bobbin holder. Accordingly, when the degrees of freedom of the mass body are provided in this plane, vibration energy is efficiently absorbed. This configuration is particularly effective if the bobbin holder is supported in such a manner as to project from the body frame.
The present invention is a yarn winder, characterized in that the mass body is held on the regulation member at its centroidal position.
When the mass body is held on the regulation member at its centroidal position, the impact damper functions effectively to enhance a vibration suppressing effect.
Alternatively, the mass body preferably holds the regulation member in such a manner as to have degrees of freedom in a plurality of directions. This is because the vibration does not always occur in a constant direction because the yarn winder vibrates due to a combination of complicated factors. For example, by forming a ring-shaped gap between the mass body and the regulation member, the plurality of degrees of freedom can be easily provided for the mass body.
Alternatively, an elastic body may be provided to reduce impact sounds. In this case, the elastic body must also be interposed between the mass body and the regulation member so that the mass body can collide against the regulation member.
Alternatively, the impact damper is preferably provided at a tip of the bobbin holder. If the yarn winder has a touch roller in contact with the bobbin holder via the package and a bracket supporting the touch roller is supported in such a manner as to project from the body frame, then the impact damper is preferably provided on a tip surface of the bracket because this arrangement enhances the vibration suppressing effect.